WO2024047364A1 - A method for coating a component of an electrolyser - Google Patents
A method for coating a component of an electrolyser Download PDFInfo
- Publication number
- WO2024047364A1 WO2024047364A1 PCT/GB2023/052266 GB2023052266W WO2024047364A1 WO 2024047364 A1 WO2024047364 A1 WO 2024047364A1 GB 2023052266 W GB2023052266 W GB 2023052266W WO 2024047364 A1 WO2024047364 A1 WO 2024047364A1
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- WO
- WIPO (PCT)
- Prior art keywords
- platinum
- component
- reducing agent
- cations
- solution
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 53
- 238000000576 coating method Methods 0.000 title claims abstract description 23
- 239000011248 coating agent Substances 0.000 title claims abstract description 21
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 63
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 48
- -1 platinum cations Chemical class 0.000 claims abstract description 41
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 40
- 239000003929 acidic solution Substances 0.000 claims abstract description 17
- 239000000243 solution Substances 0.000 claims description 24
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 20
- 238000001035 drying Methods 0.000 claims description 19
- 239000010936 titanium Substances 0.000 claims description 17
- 229910052719 titanium Inorganic materials 0.000 claims description 17
- 239000002253 acid Substances 0.000 claims description 12
- CLSUSRZJUQMOHH-UHFFFAOYSA-L platinum dichloride Chemical compound Cl[Pt]Cl CLSUSRZJUQMOHH-UHFFFAOYSA-L 0.000 claims description 12
- 238000011068 loading method Methods 0.000 claims description 9
- UORVGPXVDQYIDP-UHFFFAOYSA-N borane Chemical compound B UORVGPXVDQYIDP-UHFFFAOYSA-N 0.000 claims description 7
- 230000001680 brushing effect Effects 0.000 claims description 7
- 150000004678 hydrides Chemical class 0.000 claims description 7
- 238000005507 spraying Methods 0.000 claims description 7
- XYFCBTPGUUZFHI-UHFFFAOYSA-N Phosphine Chemical compound P XYFCBTPGUUZFHI-UHFFFAOYSA-N 0.000 claims description 6
- 229910000085 borane Inorganic materials 0.000 claims description 4
- 238000003618 dip coating Methods 0.000 claims description 4
- FXGFZZYDXMUETH-UHFFFAOYSA-L difluoroplatinum Chemical compound F[Pt]F FXGFZZYDXMUETH-UHFFFAOYSA-L 0.000 claims description 3
- 229910000073 phosphorus hydride Inorganic materials 0.000 claims description 3
- KGRJUMGAEQQVFK-UHFFFAOYSA-L platinum(2+);dibromide Chemical compound Br[Pt]Br KGRJUMGAEQQVFK-UHFFFAOYSA-L 0.000 claims description 3
- FBEIPJNQGITEBL-UHFFFAOYSA-J tetrachloroplatinum Chemical group Cl[Pt](Cl)(Cl)Cl FBEIPJNQGITEBL-UHFFFAOYSA-J 0.000 claims description 3
- 239000012279 sodium borohydride Substances 0.000 claims description 2
- 229910000033 sodium borohydride Inorganic materials 0.000 claims description 2
- BEOOHQFXGBMRKU-UHFFFAOYSA-N sodium cyanoborohydride Chemical compound [Na+].[B-]C#N BEOOHQFXGBMRKU-UHFFFAOYSA-N 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 description 12
- 239000002184 metal Substances 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 6
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000007747 plating Methods 0.000 description 5
- 238000006722 reduction reaction Methods 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 4
- 238000005868 electrolysis reaction Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 239000013626 chemical specie Substances 0.000 description 3
- 239000000470 constituent Substances 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 229910021645 metal ion Inorganic materials 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000004408 titanium dioxide Substances 0.000 description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000007772 electroless plating Methods 0.000 description 2
- 238000009713 electroplating Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 239000005518 polymer electrolyte Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000010970 precious metal Substances 0.000 description 2
- 239000012266 salt solution Substances 0.000 description 2
- 238000001350 scanning transmission electron microscopy Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- RIOQSEWOXXDEQQ-UHFFFAOYSA-N triphenylphosphine Chemical compound C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1 RIOQSEWOXXDEQQ-UHFFFAOYSA-N 0.000 description 2
- XMIIGOLPHOKFCH-UHFFFAOYSA-N 3-phenylpropionic acid Chemical compound OC(=O)CCC1=CC=CC=C1 XMIIGOLPHOKFCH-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 101100326607 Danio rerio cahz gene Proteins 0.000 description 1
- 229910020808 NaBF Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000005844 autocatalytic reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000001493 electron microscopy Methods 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 229910052987 metal hydride Inorganic materials 0.000 description 1
- 150000004681 metal hydrides Chemical class 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 150000003003 phosphines Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 150000003057 platinum Chemical class 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 238000004627 transmission electron microscopy Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/02—Hydrogen or oxygen
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/1601—Process or apparatus
- C23C18/1633—Process of electroless plating
- C23C18/1655—Process features
- C23C18/1658—Process features with two steps starting with metal deposition followed by addition of reducing agent
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/42—Coating with noble metals
- C23C18/44—Coating with noble metals using reducing agents
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/54—Contact plating, i.e. electroless electrochemical plating
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
- C25B11/03—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form perforated or foraminous
- C25B11/031—Porous electrodes
- C25B11/032—Gas diffusion electrodes
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/13—Single electrolytic cells with circulation of an electrolyte
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/60—Constructional parts of cells
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/60—Constructional parts of cells
- C25B9/65—Means for supplying current; Electrode connections; Electric inter-cell connections
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/70—Assemblies comprising two or more cells
- C25B9/73—Assemblies comprising two or more cells of the filter-press type
- C25B9/75—Assemblies comprising two or more cells of the filter-press type having bipolar electrodes
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/18—Pretreatment of the material to be coated
- C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
- C23C18/1824—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment
- C23C18/1827—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment only one step pretreatment
- C23C18/1834—Use of organic or inorganic compounds other than metals, e.g. activation, sensitisation with polymers
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/02—Hydrogen or oxygen
- C25B1/04—Hydrogen or oxygen by electrolysis of water
Definitions
- This invention relates to polymer electrolyte membrane water electrolysers (which are also referred to as electrochemical hydrogen generators), and more particularly, to a method for coating a component of such electrolysers with platinum.
- PEM water electrolysis cells are electrochemical devices that dissociate water to produce hydrogen and oxygen gases. The hydrogen produced by these devices provides a clean energy fuel source for hydrogen fuel cells.
- PEM water electrolysis cells include a cathode, an anode and a polymeric electrolyte. Additional components include bipolar plates, porous transport layers, and flow disruptors, which are typically constructed from titanium. Titanium is a preferred metal over iron and nickel- based materials which are prone to degradation.
- PEM electrolysis is beneficial over other types of electrolysis because it is more efficient and the hydrogen produced has a high level of purity and can be produced under pressure.
- the efficiency is limited by resistances within the cell. At the beginning of operation, this is dominated by the membrane.
- the cell voltage begins to deteriorate. This is primarily due to an increase of the contact resistances within the cell, which is ultimately due to a build-up (thickening) of a titanium dioxide layer on the titanium components.
- a build-up (thickening) of a titanium dioxide layer on the titanium components When the titanium dioxide layer reaches a thickness greater than the tunnelling distance of an electron (1.23 nm), an exponential rise in operating voltage results, leading to catastrophic failure of the cell. This typically takes around 5,000 - 10,000 hours of operation to manifest but can occur sooner or later depending on other factors such as operating conditions and the materials of construction of the balance of plant.
- the components are typically coated with a precious metal, such as gold or a platinum group metal (e.g. platinum, iridium, palladium, rhodium, or ruthenium).
- a precious metal such as gold or a platinum group metal (e.g. platinum, iridium, palladium, rhodium, or ruthenium).
- platinum group metal e.g. platinum, iridium, palladium, rhodium, or ruthenium.
- Plating encompasses electroplating and electroless plating, both of which involve immersing a component in a solution of metal ions and reducing the metal ions at the surface of the component to produce a metal coating. Electroplating uses electrical current to reduce the metal ions.
- a drawback of this process is that in order to plate large component parts in a production environment, the plating vessel (containing the plating bath) must be large enough to accommodate the whole component and must accordingly contain considerable quantities of the precious metal. The plating bath is therefore an expensive asset for a company to hold and this results in production costs being high.
- Electroless plating creates a metal coating by autocatalytic chemical reduction of the metal cations in which the metal itself acts as a catalytic reducing agent.
- it is unsuitable for coating electrolyser components in a production process because the period required for autocatalysis to complete is too long.
- Electroless coating methods include thermal decomposition methods and powder sintering methods, both of which must be performed at high temperatures (e.g. at greater than about 300 °C).
- a metal salt solution containing the electrode active coating material is applied, dried, and heat-treated in air at a temperature of, for example, 350 °C to 550 °C.
- platinum metal salts used in these processes include chloroplatinic acid and dinitrodiamineplatinum.
- a disadvantage of using these methods is the high operating cost associated with using such elevated temperatures, which limits their use in high volume production processes.
- Vapour deposition similarly suffers from drawbacks in that it requires expensive equipment and high vacuum techniques which are difficult to use in large scale production.
- a method of coating a component of an electrolyser, wherein the component comprises titanium comprising: applying an acidic solution of platinum cations to at least a portion of the component, and reducing the applied platinum cations with a reducing agent to form a layer of platinum metal on the component.
- the method of the present invention is low cost and is suitable for use in high volume manufacturing processes. It can be performed at low temperature (e.g. below 350 °C) and does not result in oxidation of the component's metal.
- the method may further comprise at least partially drying the applied acidic solution of platinum cations.
- the drying may be carried out at a temperature of from about 0 °C to 200 °C, from about 25 °C to 175 °C, from about 50 °C to 150 °C, from about 75 °C to 125 °C, from about 80 °C to 100 °C, from about 90 °C to 95 °C, or at a temperature below about 350 °C.
- the temperature of the drying step is considerably lower than the temperatures used in thermal decomposition and powder sintering methods of the prior art. This provides a process which is easier to operate and has reduced operating costs.
- the acidic solution of platinum cations may be applied to the component in an amount sufficient to provide a platinum loading of from about 0.01 mg/cm 2 to 2.5 mg/cm 2 on the component. This loading range is comparable to the catalyst loading of conventional commercial components.
- the component may be selected from the group consisting of one or more of a cathode compartment or chamber, an anode compartment or chamber, a bipolar plate, a flow disruptor, and a porous transport layer.
- the acidic solution of platinum cations may be applied to the component by one or more methods selected from the group consisting of brushing, dip coating, spraying, and combinations thereof. These application methods ensure an even coating of platinum cations on the component, or a target portion thereof, as required.
- the applied platinum cations may be reduced by contact with the reducing agent.
- the contact may include brushing the applied platinum cations with a solution comprising the reducing agent, immersing the component in a solution comprising the reducing agent, spraying the component with a solution comprising the reducing agent, or a combination thereof.
- the contact may preferably include immersing the component in a solution comprising the reducing agent.
- the drying may be carried out at a temperature of from about 0 °C to 200 °C, from about 25 °C to 175 °C, from about 50 °C to 150 °C, from about 75 °C to 125 °C, from about 80 °C to 100 °C, from about 90 °C to 95 °C, or at a temperature below about 350 °C.
- Drying removes the solvent in which the reducing agent may be present and may serve to accelerate the reduction reaction by concentrating the reducing agent which is in contact with the platinum cations.
- the acidic solution of platinum cations may comprise from about 1 wt% to 20 wt%, from about 5 wt% to 15 wt%, or about 10 wt% HCI.
- the HCI maintains the platinum cations in a charged state and limits side reactions.
- the acidic solution of platinum cations may comprise a platinum halide, preferably selected from one or more of platinum chloride, platinum bromide and/or platinum fluoride.
- the platinum halide may comprise platinum chloride and the platinum chloride may be selected from platinum(IV) chloride, chloroplatinic acid (HzPtCle), and platinum(II) chloride.
- the reducing agent may comprise a hydride, a phosphine and/or a borane reducing agent.
- the hydride reducing agent may be selected from sodium borohydride and/or sodium cyanoborohydride.
- Figure 1 is a graph illustrating differences in interfacial contact resistance between titanium components which have been coated and undergone an accelerated corrosion test according to the method of the present invention and uncoated titanium components.
- Consisting essentially of with respect to the constituents of a component will be understood to mean that the component contains the indicated constituents but may also contain minor trace quantities (i.e. less than 5 wt%, preferably less than 1 wt%) of other constituents or additives without substantially altering the chemical or physical properties of the component.
- the term "about” in relation to the amounts expressed means that the stated amount can vary by ⁇ 5% of the stated amount.
- about 90 wt% means 90 ⁇ 5 wt%
- about 0.1 wt% means 0.1 ⁇ 0.005 wt%
- about 80 °C means 80 ⁇ 4 °C.
- the term “about” applies to all values in the range.
- reducing agent also called a reductant or a reducer
- reducing agent refers to a chemical species which participates in a redox reaction by reducing another chemical species. It donates at least one electron and in doing so becomes oxidised.
- reducing agents include hydrides, such as metal hydrides (e.g. NaH, LiH, CaHz, LiAIF and Red-AI) and borohydrides (e.g. NaBFU, NaBHsCN and LiBFU), boranes, and phosphines (e.g. triphenylphosphine).
- the reducing agent referred to in the present disclosure may comprise one or more chemical species selected from these groups.
- the present disclosure provides a method of coating a component of an electrolyser.
- the coating minimise interfacial contact resistance by preventing titanium dioxide from forming during operation of the electrolyser, which maintains the efficiency of the electrolyser cell and prolongs its lifetime.
- the method comprises applying an acidic solution of platinum cations to at least a portion of the component and reducing the applied platinum cations with a reducing agent to form a layer of platinum metal on the component.
- the coating produced may be continuous or discontinuous, or a combination thereof.
- the degree of continuity of the coating may be determined by electron microscopy, for example, transmission electron microscopy (TEM), scanning electron microscopy (SEM), or scanning transmission electron microscopy (STEM), although any suitable method may be used.
- the acidic solution of platinum cations may be applied to the component by one or more application methods selected from the group consisting of brushing, dip coating, spraying, and combinations thereof. More than one application method may be used where the method of the invention is performed in multiple cycles. For example, a first cycle may comprise dip coating and a second cycle may comprise spraying. The use of combinations of different methods may permit a desired platinum loading to be achieved, since different methods typically apply different volumes of solution to the component surface.
- the acidic solution of platinum cations may comprise from 0.1 M to 5 M, from 0.5 M to 2 M, from 0.5 to 1.5 M, or about IM of an acid, or from about 1 wt% to 20 wt%, from about 5 wt% to 15 wt%, or about 10 wt% of an acid.
- the acid may be selected from HCI, H2SO4, HNO3, and CH3COOH, and is preferably HCI.
- the platinum cations may comprise a platinum halide or dinitrodiamineplatinum.
- the platinum halide may preferably be selected from one or more of platinum chloride, platinum bromide and/or platinum fluoride. Platinum chlorides are particularly preferred since the chloride anion is also present in the preferred acid, HCI.
- the platinum chloride may be selected from platinum(IV) chloride, chloroplatinic acid (HzPtCle), and platinum(II) chloride. In a preferred embodiment, the platinum cations comprise chloroplatinic acid.
- the acidic solution of platinum cations may be applied to the component in an amount sufficient to provide a platinum loading of from about 0.01 mg/cm 2 to 2.5 mg/cm 2 , from about 0.01 mg/cm 2 to 2.0 mg/cm 2 , from about 1.0 mg/cm 2 to 2.0 mg/cm 2 , from about 1.25 mg/cm 2 to 1.5 mg/cm 2 , from about 0.1 mg/cm 2 to 2.0 mg/cm 2 , from about 0.01 mg/cm 2 to 1.5 mg/cm 2 , or from about 0.01 mg/cm 2 to 1 mg/cm 2 on the component.
- the method may be performed iteratively or more than once (i.e. over multiple cycles) to achieve a desired platinum loading. For example, the method may be performed from 2 to 50 times, from 2 to 20 times, from 2 to 15 times, from 2 to 10 times or from 2 to 5 times.
- the method may further comprise at least partially drying the component after application of the solution.
- the acid solution is typically an aqueous solution and the drying step removes substantially all of the water to leave a residue of the platinum cations on the surface of the component.
- the drying step may be carried out at a temperature of from about 0 °C to 200 °C, from about 25 °C to 175 °C, from about 50 °C to 150 °C, from about 75 °C to 125 °C, from about 80 °C to 100 °C, from about 90 °C to 95 °C, or at a temperature below about 350 °C, 300 °C, 250 °C, 200 °C, 150 °C, 100 °C or 95 °C.
- a gas such as air, may be passed over the surface of the component to accelerate drying. The gas may optionally be heated.
- the component may be selected from the group consisting of one or more of a cathode compartment or chamber, an anode compartment or chamber, a bipolar plate, a flow disruptor and a porous transport layer.
- the component may be a bipolar plate or a porous transport layer.
- the component may be constructed from a material comprising titanium.
- the component may consist essentially of titanium prior to coating.
- the component may be a titanium component.
- the component may comprise at least 80 wt%, at least 85 wt%, at least 90wt%, at least 95 wt%, at least 96 wt%, at least 97 wt%, at least 98 wt%, at least 99 wt%, 100 wt% titanium, or a range between any two of these values.
- the reducing agent is a chemical reductant which may comprise a hydride, a borane and/or a phosphine reducing agent.
- the reducing agent comprises a hydride, more preferably a borohydride, or even more preferably NaBF and/or NaBHsCN.
- the reducing agent may be present as a solution, for example, an aqueous solution.
- the reducing step includes contacting the applied platinum cations with the reducing agent.
- the contact may include brushing the applied platinum cations with a solution comprising the reducing agent, immersing the component in a solution comprising the reducing agent, spraying the component with a solution comprising the reducing agent, or a combination thereof.
- the contacting may preferably include immersing the component in a solution comprising the reducing agent.
- the component may be washed to remove any salts or impurities remaining after the reduction.
- the method may further comprise at least partially drying the component.
- the drying step removes any water which may be present on the surface of the component.
- the drying step may be carried out at a temperature of from about 0 °C to 200 °C, from about 25 °C to 175 °C, from about 50 °C to 150 °C, from about 75 °C to 125 °C, from about 80 °C to 100 °C, from about 90 °C to 95 °C, or at a temperature below about 350 °C, 300 °C, 250 °C, 200 °C, 150 °C, 100 °C or 95 °C.
- a gas such as air, may be passed over the surface of the component to accelerate drying. The gas may optionally be heated.
- a piece of titanium sheet metal cut and machined to size (20 cm x 20 cm) was first cleaned in water then degreased in a batch of acetone in an ultrasonic bath for about 10 minutes. After drying the piece was rinsed three times with deionised water.
- a coating solution was made by dissolving 10g of chloroplatinic acid (HzPtCle) in a IM hydrochloric acid solution. The solution was applied to the previously prepared titanium piece by brushing, reaching a chloroplatinic acid salt solution loading of 12.5-15.0 g/m 2 .
- the coated part was dried at 90°C and reweighed to ensure a loading of 1.25-1.5 g/m 2 of HzPtCle.
- the dried part was instantaneously then dipped into a IM NazBF solution for 2 seconds.
- the platinum salt was reduced to platinum on the surface of the titanium, as evidenced by the appearance of bubbles of hydrogen on the surface of the part.
- titanium part was placed in an aqueous solution containing 1 mg/l NaF (2.4 xlO' 5 M) for 1 hour.
- An uncoated (degreased) titanium part was placed in the same solution for the same amount of time. After 1 hour both parts were rinsed in deionised water and dried at 90°C.
- the contact resistance of the parts was measured by placing 1 cm 2 gold coated copper disc on the surface with a pressure of 1.96 N/cm 2 . A current of 1A was passed between the copper disc and the titanium part and the voltage between the copper disc and the titanium was measured using a calibrated digital voltmeter. Using Ohms law the voltage was converted directly into a contact resistance in Q.cm 2 .
- the coated part had a contact resistance of between 1 and 6 mQ.cm 2 , whereas the uncoated part had a contact resistance above 100 mQ.cm 2 .
- Table 1 below and illustrated in Figure 1.
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Abstract
A method of coating a component of an electrolyser is provided. The method comprises applying an acidic solution of platinum cations to at least a portion of the component and reducing the applied platinum cations with a reducing agent to form a layer of platinum metal on the component.
Description
A METHOD FOR COATING A COMPONENT OF AN ELECTROLYSER
FIELD OF THE INVENTION
This invention relates to polymer electrolyte membrane water electrolysers (which are also referred to as electrochemical hydrogen generators), and more particularly, to a method for coating a component of such electrolysers with platinum.
BACKGROUND
Polymer electrolyte membrane (PEM) water electrolysis cells are electrochemical devices that dissociate water to produce hydrogen and oxygen gases. The hydrogen produced by these devices provides a clean energy fuel source for hydrogen fuel cells. PEM water electrolysis cells include a cathode, an anode and a polymeric electrolyte. Additional components include bipolar plates, porous transport layers, and flow disruptors, which are typically constructed from titanium. Titanium is a preferred metal over iron and nickel- based materials which are prone to degradation.
PEM electrolysis is beneficial over other types of electrolysis because it is more efficient and the hydrogen produced has a high level of purity and can be produced under pressure. However, the efficiency is limited by resistances within the cell. At the beginning of operation, this is dominated by the membrane. However, over time the cell voltage begins to deteriorate. This is primarily due to an increase of the contact resistances within the cell, which is ultimately due to a build-up (thickening) of a titanium dioxide layer on the titanium components. When the titanium dioxide layer reaches a thickness greater than the tunnelling distance of an electron (1.23 nm), an exponential rise in operating voltage results, leading to catastrophic failure of the cell. This typically takes around 5,000 - 10,000 hours of operation to manifest but can occur sooner or later depending on other factors such as operating conditions and the materials of construction of the balance of plant.
To resolve this issue, the components are typically coated with a precious metal, such as gold or a platinum group metal (e.g. platinum, iridium, palladium, rhodium, or ruthenium). The coating does not need to be continuous as its primary use is metal to metal and metal to catalyst contact resistance.
Two common methodologies for coating titanium components are plating and physical (or chemical) vapour deposition.
Plating encompasses electroplating and electroless plating, both of which involve immersing a component in a solution of metal ions and reducing the metal ions at the surface of the component to produce a metal coating. Electroplating uses electrical current to reduce the metal ions. A drawback of this process is that in order to plate large component parts in a production environment, the plating vessel (containing the plating bath) must be large enough to accommodate the whole component and must accordingly contain considerable quantities of the precious metal. The plating bath is therefore an expensive asset for a company to hold and this results in production costs being high.
Electroless plating creates a metal coating by autocatalytic chemical reduction of the metal cations in which the metal itself acts as a catalytic reducing agent. However, it is unsuitable for coating electrolyser components in a production process because the period required for autocatalysis to complete is too long.
Other electroless coating methods include thermal decomposition methods and powder sintering methods, both of which must be performed at high temperatures (e.g. at greater than about 300 °C). A metal salt solution containing the electrode active coating material is applied, dried, and heat-treated in air at a temperature of, for example, 350 °C to 550 °C. Examples of platinum metal salts used in these processes include chloroplatinic acid and dinitrodiamineplatinum. A disadvantage of using these methods is the high operating cost associated with using such elevated temperatures, which limits their use in high volume production processes.
Vapour deposition similarly suffers from drawbacks in that it requires expensive equipment and high vacuum techniques which are difficult to use in large scale production.
There is accordingly a need for a method of coating a component of an electrolyser which addresses the above problems, at least to some extent.
SUMMARY OF THE INVENTION
In accordance with this invention, there is provided a method of coating a component of an electrolyser, wherein the component comprises titanium, the method comprising: applying an acidic solution of platinum cations to at least a portion of the component, and reducing the applied platinum cations with a reducing agent to form a layer of platinum metal on the component.
In contrast to existing coating methods, the method of the present invention is low cost and is suitable for use in high volume manufacturing processes. It can be performed at low temperature (e.g. below 350 °C) and does not result in oxidation of the component's metal.
The method may further comprise at least partially drying the applied acidic solution of platinum cations. The drying may be carried out at a temperature of from about 0 °C to 200 °C, from about 25 °C to 175 °C, from about 50 °C to 150 °C, from about 75 °C to 125 °C, from about 80 °C to 100 °C, from about 90 °C to 95 °C, or at a temperature below about 350 °C.
The temperature of the drying step is considerably lower than the temperatures used in thermal decomposition and powder sintering methods of the prior art. This provides a process which is easier to operate and has reduced operating costs.
The acidic solution of platinum cations may be applied to the component in an amount sufficient to provide a platinum loading of from about 0.01 mg/cm2 to 2.5 mg/cm2 on the component. This loading range is comparable to the catalyst loading of conventional commercial components.
The component may be selected from the group consisting of one or more of a cathode compartment or chamber, an anode compartment or chamber, a bipolar plate, a flow disruptor, and a porous transport layer.
The acidic solution of platinum cations may be applied to the component by one or more methods selected from the group consisting of brushing, dip coating, spraying, and combinations thereof. These application methods ensure an even coating of platinum cations on the component, or a target portion thereof, as required.
The applied platinum cations may be reduced by contact with the reducing agent. The contact may include brushing the applied platinum cations with a solution comprising the reducing agent, immersing the component in a solution comprising the reducing agent, spraying the component with a solution comprising the reducing agent, or a combination thereof. The contact may preferably include immersing the component in a solution comprising the reducing agent. These contacting methods allow for a maximum degree of reduction of the platinum cations to be achieved resulting in a uniform coating of platinum metal on the component.
The method may further comprise at least partially drying the component after reduction of the platinum cations. For example, the drying may be performed after immersion of the component in a solution of the reducing agent. The drying may be carried out at a temperature of from about 0 °C to 200 °C, from about 25 °C to 175 °C, from about 50 °C to 150 °C, from about 75 °C to 125 °C, from about 80 °C to 100 °C, from about 90 °C to 95 °C, or at a temperature below about 350 °C.
Drying removes the solvent in which the reducing agent may be present and may serve to accelerate the reduction reaction by concentrating the reducing agent which is in contact with the platinum cations.
The acidic solution of platinum cations may comprise from about 1 wt% to 20 wt%, from about 5 wt% to 15 wt%, or about 10 wt% HCI. The HCI maintains the platinum cations in a charged state and limits side reactions.
The acidic solution of platinum cations may comprise a platinum halide, preferably selected from one or more of platinum chloride, platinum bromide and/or platinum fluoride. The platinum halide may comprise platinum chloride and the platinum chloride may be selected from platinum(IV) chloride, chloroplatinic acid (HzPtCle), and platinum(II) chloride.
The reducing agent may comprise a hydride, a phosphine and/or a borane reducing agent. The hydride reducing agent may be selected from sodium borohydride and/or sodium cyanoborohydride.
BRIEF DESCRIPTION OF THE FIGURE
In the accompanying Figure:
Figure 1 is a graph illustrating differences in interfacial contact resistance between titanium components which have been coated and undergone an accelerated corrosion test according to the method of the present invention and uncoated titanium components.
DETAILED DESCRIPTION
As used herein and in the accompanying claims, unless the context requires otherwise, "comprise" or variations such as "comprises" or "comprising" will be understood to imply
the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
"Consisting essentially of" with respect to the constituents of a component will be understood to mean that the component contains the indicated constituents but may also contain minor trace quantities (i.e. less than 5 wt%, preferably less than 1 wt%) of other constituents or additives without substantially altering the chemical or physical properties of the component.
As used herein, the term "about" in relation to the amounts expressed means that the stated amount can vary by ± 5% of the stated amount. For example, about 90 wt% means 90±5 wt%, about 0.1 wt% means 0.1±0.005 wt%, about 80 °C means 80±4 °C. When used with reference to a range, the term "about" applies to all values in the range.
As used herein, the term "reducing agent" (also called a reductant or a reducer) refers to a chemical species which participates in a redox reaction by reducing another chemical species. It donates at least one electron and in doing so becomes oxidised. Examples of reducing agents include hydrides, such as metal hydrides (e.g. NaH, LiH, CaHz, LiAIF and Red-AI) and borohydrides (e.g. NaBFU, NaBHsCN and LiBFU), boranes, and phosphines (e.g. triphenylphosphine). The reducing agent referred to in the present disclosure may comprise one or more chemical species selected from these groups.
The present disclosure provides a method of coating a component of an electrolyser. The coating minimise interfacial contact resistance by preventing titanium dioxide from forming during operation of the electrolyser, which maintains the efficiency of the electrolyser cell and prolongs its lifetime. The method comprises applying an acidic solution of platinum cations to at least a portion of the component and reducing the applied platinum cations with a reducing agent to form a layer of platinum metal on the component. The coating produced may be continuous or discontinuous, or a combination thereof. The degree of continuity of the coating may be determined by electron microscopy, for example, transmission electron microscopy (TEM), scanning electron microscopy (SEM), or scanning transmission electron microscopy (STEM), although any suitable method may be used.
The acidic solution of platinum cations may be applied to the component by one or more application methods selected from the group consisting of brushing, dip coating, spraying, and combinations thereof. More than one application method may be used where the method of the invention is performed in multiple cycles. For example, a first cycle may comprise dip coating and a second cycle may comprise spraying. The use of combinations
of different methods may permit a desired platinum loading to be achieved, since different methods typically apply different volumes of solution to the component surface.
The acidic solution of platinum cations may comprise from 0.1 M to 5 M, from 0.5 M to 2 M, from 0.5 to 1.5 M, or about IM of an acid, or from about 1 wt% to 20 wt%, from about 5 wt% to 15 wt%, or about 10 wt% of an acid. The acid may be selected from HCI, H2SO4, HNO3, and CH3COOH, and is preferably HCI.
The platinum cations may comprise a platinum halide or dinitrodiamineplatinum. The platinum halide may preferably be selected from one or more of platinum chloride, platinum bromide and/or platinum fluoride. Platinum chlorides are particularly preferred since the chloride anion is also present in the preferred acid, HCI. The platinum chloride may be selected from platinum(IV) chloride, chloroplatinic acid (HzPtCle), and platinum(II) chloride. In a preferred embodiment, the platinum cations comprise chloroplatinic acid.
The acidic solution of platinum cations may be applied to the component in an amount sufficient to provide a platinum loading of from about 0.01 mg/cm2 to 2.5 mg/cm2, from about 0.01 mg/cm2 to 2.0 mg/cm2, from about 1.0 mg/cm2 to 2.0 mg/cm2, from about 1.25 mg/cm2 to 1.5 mg/cm2, from about 0.1 mg/cm2 to 2.0 mg/cm2, from about 0.01 mg/cm2 to 1.5 mg/cm2, or from about 0.01 mg/cm2 to 1 mg/cm2 on the component. The method may be performed iteratively or more than once (i.e. over multiple cycles) to achieve a desired platinum loading. For example, the method may be performed from 2 to 50 times, from 2 to 20 times, from 2 to 15 times, from 2 to 10 times or from 2 to 5 times.
The method may further comprise at least partially drying the component after application of the solution. The acid solution is typically an aqueous solution and the drying step removes substantially all of the water to leave a residue of the platinum cations on the surface of the component. The drying step may be carried out at a temperature of from about 0 °C to 200 °C, from about 25 °C to 175 °C, from about 50 °C to 150 °C, from about 75 °C to 125 °C, from about 80 °C to 100 °C, from about 90 °C to 95 °C, or at a temperature below about 350 °C, 300 °C, 250 °C, 200 °C, 150 °C, 100 °C or 95 °C. A gas, such as air, may be passed over the surface of the component to accelerate drying. The gas may optionally be heated.
The component may be selected from the group consisting of one or more of a cathode compartment or chamber, an anode compartment or chamber, a bipolar plate, a flow disruptor and a porous transport layer. For example, the component may be a bipolar
plate or a porous transport layer. The component may be constructed from a material comprising titanium. The component may consist essentially of titanium prior to coating. For example, the component may be a titanium component. The component may comprise at least 80 wt%, at least 85 wt%, at least 90wt%, at least 95 wt%, at least 96 wt%, at least 97 wt%, at least 98 wt%, at least 99 wt%, 100 wt% titanium, or a range between any two of these values.
The reducing agent is a chemical reductant which may comprise a hydride, a borane and/or a phosphine reducing agent. Preferably, the reducing agent comprises a hydride, more preferably a borohydride, or even more preferably NaBF and/or NaBHsCN. The reducing agent may be present as a solution, for example, an aqueous solution.
The reducing step includes contacting the applied platinum cations with the reducing agent. The contact may include brushing the applied platinum cations with a solution comprising the reducing agent, immersing the component in a solution comprising the reducing agent, spraying the component with a solution comprising the reducing agent, or a combination thereof. The contacting may preferably include immersing the component in a solution comprising the reducing agent. The component may be washed to remove any salts or impurities remaining after the reduction.
The method may further comprise at least partially drying the component. When the reducing agent is present as a solution, it is typically present as an aqueous solution and the drying step removes any water which may be present on the surface of the component. The drying step may be carried out at a temperature of from about 0 °C to 200 °C, from about 25 °C to 175 °C, from about 50 °C to 150 °C, from about 75 °C to 125 °C, from about 80 °C to 100 °C, from about 90 °C to 95 °C, or at a temperature below about 350 °C, 300 °C, 250 °C, 200 °C, 150 °C, 100 °C or 95 °C. A gas, such as air, may be passed over the surface of the component to accelerate drying. The gas may optionally be heated.
EXAMPLE
A piece of titanium sheet metal cut and machined to size (20 cm x 20 cm) was first cleaned in water then degreased in a batch of acetone in an ultrasonic bath for about 10 minutes. After drying the piece was rinsed three times with deionised water. A coating solution was made by dissolving 10g of chloroplatinic acid (HzPtCle) in a IM hydrochloric acid solution. The solution was applied to the previously prepared titanium piece by brushing, reaching a chloroplatinic acid salt solution loading of 12.5-15.0 g/m2. The coated part was dried at 90°C and reweighed to ensure a loading of 1.25-1.5 g/m2 of HzPtCle. The dried part was
instantaneously then dipped into a IM NazBF solution for 2 seconds. The platinum salt was reduced to platinum on the surface of the titanium, as evidenced by the appearance of bubbles of hydrogen on the surface of the part.
To simulate the effects of accelerated corrosion in an electrolyser cell the titanium part was placed in an aqueous solution containing 1 mg/l NaF (2.4 xlO'5 M) for 1 hour. An uncoated (degreased) titanium part was placed in the same solution for the same amount of time. After 1 hour both parts were rinsed in deionised water and dried at 90°C.
The contact resistance of the parts was measured by placing 1 cm2 gold coated copper disc on the surface with a pressure of 1.96 N/cm2. A current of 1A was passed between the copper disc and the titanium part and the voltage between the copper disc and the titanium was measured using a calibrated digital voltmeter. Using Ohms law the voltage was converted directly into a contact resistance in Q.cm2. The coated part had a contact resistance of between 1 and 6 mQ.cm2, whereas the uncoated part had a contact resistance above 100 mQ.cm2. The results are provided in Table 1 below and illustrated in Figure 1.
Claims
1. A method of coating a component of an electrolyser, wherein the component comprises titanium, the method comprising: applying an acidic solution of platinum cations to at least a portion of the component, and reducing the applied platinum cations with a reducing agent to form a layer of platinum metal on the component.
2. The method of claim 1, further comprising at least partially drying the applied acidic solution of platinum cations.
3. The method of claim 2, wherein the drying is carried out at a temperature of from 0 °C to 200 °C, from about 25 °C to 175 °C, from about 50 °C to 150 °C, from about 75 °C to 125 °C, from about 80 °C to 100 °C, from about 90 °C to 95 °C, or at a temperature below about 350 °C.
4. The method of any preceding claim, wherein the acidic solution of platinum cations is applied to the component in an amount sufficient to provide a platinum loading of from 0.01 to 2.5 mg/cm2 on the component.
5. The method of any preceding claim, wherein the component is selected from one or more of a cathode compartment or chamber, an anode compartment or chamber, a flow disruptor and a bipolar plate.
6. The method of any preceding claim, wherein the component is a titanium component.
7. The method of any preceding claim, wherein the acidic solution of platinum cations is applied to the component by a method selected from the group consisting of brushing, dip coating, spraying, or a combination thereof.
8. The method of any preceding claim, wherein the reducing includes brushing the applied platinum cations with a solution comprising the reducing agent, immersing the component in a solution comprising the reducing agent, spraying the component with a solution comprising the reducing agent, or a combination thereof.
The method of any preceding claim, wherein the reducing comprises immersing the component in a solution comprising the reducing agent. The method of any preceding claim, further comprising drying the component after the contacting step. The method of any preceding claim, wherein the acidic solution of platinum cations comprises from 1 wt% to 20 wt%, from 5 wt% to 15 wt%, or 10 wt% HCI. The method of any preceding claim, wherein the acidic solution of platinum cations comprises a platinum halide, preferably selected from one or more of platinum chloride, platinum bromide and/or platinum fluoride. The method of claim 12, wherein the platinum halide comprises platinum chloride and the platinum chloride is selected from platinum(IV) chloride, chloroplatinic acid (HzPtCle), and platinum(II) chloride. The method of any preceding claim, wherein the reducing agent comprises a hydride, phosphine and/or borane reducing agent. The method of claim 14, wherein the hydride reducing agent is selected from sodium borohydride and/or sodium cyanoborohydride.
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Citations (3)
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US3177131A (en) * | 1959-04-27 | 1965-04-06 | Ici Ltd | Method for the production of platinum coated titanium anodes |
JPH06173060A (en) * | 1992-12-10 | 1994-06-21 | Permelec Electrode Ltd | Gas electrode structure and electrolytic method using said structure |
CN107858701B (en) * | 2017-10-16 | 2019-08-02 | 中国科学院广州能源研究所 | A kind of titanium-based hydrogen-precipitating electrode and preparation method thereof for solid polymer water electrolyzer |
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US6821909B2 (en) * | 2002-10-30 | 2004-11-23 | Applied Materials, Inc. | Post rinse to improve selective deposition of electroless cobalt on copper for ULSI application |
EP3739678A1 (en) * | 2019-05-17 | 2020-11-18 | Paul Scherrer Institut | Method for preparing a polymer membrane for a polymer electrolyte water electrolyser |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3177131A (en) * | 1959-04-27 | 1965-04-06 | Ici Ltd | Method for the production of platinum coated titanium anodes |
JPH06173060A (en) * | 1992-12-10 | 1994-06-21 | Permelec Electrode Ltd | Gas electrode structure and electrolytic method using said structure |
CN107858701B (en) * | 2017-10-16 | 2019-08-02 | 中国科学院广州能源研究所 | A kind of titanium-based hydrogen-precipitating electrode and preparation method thereof for solid polymer water electrolyzer |
Non-Patent Citations (1)
Title |
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RAO CHEPURI R.K ET AL: "Electroless deposition of platinum on titanium substrates", MATERIALS CHEMISTRY AND PHYSICS, vol. 68, no. 1-3, 1 February 2001 (2001-02-01), Switzerland, Taiwan, Republic of China, pages 62 - 65, XP093091071, ISSN: 0254-0584, DOI: 10.1016/S0254-0584(00)00268-6 * |
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